Linux: Refactor X11DesktopHandler

ui/events/platform/x11/x11_event_source.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/platform/x11/x11_event_source.h"
 
 #include <X11/Xatom.h>
 #include <X11/XKBlib.h>
 #include <X11/Xlib.h>
 
@@ skipping 78 matching lines @@
 
 }  // namespace
 
 X11EventSource* X11EventSource::instance_ = nullptr;
 
 X11EventSource::X11EventSource(X11EventSourceDelegate* delegate,
                                XDisplay* display)
     : delegate_(delegate),
       display_(display),
       last_seen_server_time_(CurrentTime),
+      event_timestamp_(CurrentTime),
       dummy_initialized_(false),
       continue_stream_(true) {
   DCHECK(!instance_);
   instance_ = this;
 
   DCHECK(delegate_);
   DCHECK(display_);
   DeviceDataManagerX11::CreateInstance();
   InitializeXkb(display_);
 }
@@ skipping 68 matching lines @@
 
   last_seen_server_time_ = event.xproperty.time;
 
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Event.Latency.X11EventSource.UpdateServerTime",
       (base::TimeTicks::Now() - start).InMicroseconds(), 1,
       base::TimeDelta::FromMilliseconds(1).InMicroseconds(), 50);
   return last_seen_server_time_;
 }
 
+void X11EventSource::SetLastSeenServerTime(Time time) {
+  if (time != CurrentTime) {
+    int64_t event_time_64 = time;
+    int64_t time_difference = last_seen_server_time_ - event_time_64;
+    // Ignore timestamps that go backwards. However, X server time is a 32-bit
+    // millisecond counter, so if the time goes backwards by more than half the
+    // range of the 32-bit counter, treat it as a rollover.
+    if (time_difference < 0 || time_difference > (UINT32_MAX >> 1))
+      last_seen_server_time_ = time;
+  }
+}
+
+Time X11EventSource::GetTimestamp() {
+  if (event_timestamp_ != CurrentTime) {
+    return event_timestamp_;
+  }
+  DVLOG(1) << "Making a round trip to get a recent server timestamp.";
+  return UpdateLastSeenServerTime();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // X11EventSource, protected
 
 void X11EventSource::ExtractCookieDataDispatchEvent(XEvent* xevent) {
   bool have_cookie = false;
   if (xevent->type == GenericEvent &&
       XGetEventData(xevent->xgeneric.display, &xevent->xcookie)) {
     have_cookie = true;
   }
-  Time event_time = ExtractTimeFromXEvent(*xevent);
-  if (event_time != CurrentTime) {
-    int64_t event_time_64 = event_time;
-    int64_t time_difference = last_seen_server_time_ - event_time_64;
-    // Ignore timestamps that go backwards. However, X server time is a 32-bit
-    // millisecond counter, so if the time goes backwards by more than half the
-    // range of the 32-bit counter, treat it as a rollover.
-    if (time_difference < 0 || time_difference > (UINT32_MAX >> 1))
-      last_seen_server_time_ = event_time;
-  }
+
+  event_timestamp_ = ExtractTimeFromXEvent(*xevent);
+  SetLastSeenServerTime(event_timestamp_);
+
   delegate_->ProcessXEvent(xevent);
   PostDispatchEvent(xevent);
+
+  event_timestamp_ = CurrentTime;
+
   if (have_cookie)
     XFreeEventData(xevent->xgeneric.display, &xevent->xcookie);
 }
 
 void X11EventSource::PostDispatchEvent(XEvent* xevent) {
   bool should_update_device_list = false;
 
   if (xevent->type == GenericEvent) {
     if (xevent->xgeneric.evtype == XI_HierarchyChanged) {
       should_update_device_list = true;
@@ skipping 39 matching lines @@
 
 void X11EventSource::OnDispatcherListChanged() {
   if (!hotplug_event_handler_) {
     hotplug_event_handler_.reset(new X11HotplugEventHandler());
     // Force the initial device query to have an update list of active devices.
     hotplug_event_handler_->OnHotplugEvent();
   }
 }
 
 }  // namespace ui